Yes. At 18 (in the US) you are an adult. You can choose as you please. Keep in mind that you will have to live with your choices.
They can't because they are way too young.
i guess that depends on if you are the parent of the girl or you are the girl.
With parents permission but seriously too young
Yes, as friends. she is too young for more.
She Doesn't. Your too young.
yes
You're too young for that, wait about three years.
Yes, it is possible (depending on how developed the girl is, of course), for an 11-year-old boy to get a 13-year-old girl pregnant.
Not necessarily. i am 17 and am 5'4"
No, because she is too young to make a decision that important.
Tell her you like her...you never know maybe she likes you too. =)
That is too general a question to be specific. Depending on the individuals, it could be either.